Multi-zone combustor

ABSTRACT

A multi-zone combustor is provided and includes a pre-mixer configured to output a first mixture to a primary zone of a combustor section and a stepped center body disposable in an annulus defined within the pre-mixer. The stepped center body includes an outer body configured to output at a first radial and axial step a second mixture to a secondary zone of the combustor section and an inner body disposable in an annulus defined within the outer body and configured to output at a second radial and axial step a third mixture to a tertiary zone of the combustor section.

CROSS-REFERENCE TO RELATED APPLICATION

This National Stage application claims the benefit of priority to PCTInternational Application No. PCT/RU2011/00970, which was filed on Dec.5, 2011. The entire contents of PCT International Application No.PCT/RU2011/00970 are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a multi-zone combustorand, more particularly, to a multi-zone combustor having a steppedcenter body.

In gas turbine engines, a compressor compresses inlet gases to producecompressed gas. This compressed gas is transmitted to a combustor wherethe compressed gas may be mixed with fuel and combusted to produce afluid flow of high temperature fluids. These high temperature fluids aretransmitted to a turbine section in which energy of the high temperaturefluids is converted into mechanical energy for use in the production ofpower and/or electricity.

During full speed, full load operational conditions, this arrangementmay be highly efficient and tends to produce relatively little pollutantemissions. However, during turndown or part load conditions, the fueland air mixing and subsequent combustion do not occur at temperaturesand mass flow rates that lead to efficient combustion. The process maytherefore produce an increase in pollutant emissions as well asunnecessarily reduced power and/or electricity production.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a multi-zone combustor isprovided and includes a pre-mixer configured to output a first mixtureto a primary zone of a combustor section and a stepped center bodydisposable in an annulus defined within the pre-mixer. The steppedcenter body includes an outer body configured to output at a firstradial and axial step a second mixture to a secondary zone of thecombustor section and an inner body disposable in an annulus definedwithin the outer body and configured to output at a second radial andaxial step a third mixture to a tertiary zone of the combustor section.

According to another aspect of the invention, a multi-zone combustor isprovided and includes a combustor body having a head end, a combustorsection downstream from the head end and a mixing section interposedbetween the head end and the combustor section, a pre-mixer extendiblefrom the head end through the mixing section and configured to output ata first axial location a first mixture to the combustor section and astepped center body disposable in an annulus defined within thepre-mixer. The stepped center body includes an outer body configured tooutput at a second axial location downstream from the first axiallocation a second mixture to the combustor section and an inner bodydisposable in an annulus defined within the outer body and configured tooutput at a third axial location downstream from the second axiallocation a third mixture to the combustor section.

According to yet another aspect of the invention, a multi-zone combustoris provided and includes a combustor body having a head end, a combustorsection downstream from the head end and a mixing section interposedbetween the head end and the combustor section, a pre-mixer extendiblefrom the head end through the mixing section and configured to output ata first axial location a first mixture to the combustor section and astepped center body disposable in an annulus defined within thepre-mixer. The stepped center body includes an outer body configured tooutput at a second axial location downstream from the first axiallocation a second mixture to the combustor section and an inner bodydisposable in an annulus defined within the outer body and configured tooutput at a third axial location downstream from the second axiallocation a third mixture to the combustor section.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a side view of a multi-zone combustor;

FIG. 2 is an enlarged side view of a center body of the multi-zonecombustor of FIG. 1; and

FIG. 3 is an enlarged side view of the center body of FIG. 2 inaccordance with further embodiments.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a multi-zone combustor 10 of a turbomachine,such as a gas turbine engine, is provided. In the exemplary gas turbineengine, a compressor compresses inlet gases to produce compressed gas.This compressed gas is transmitted to the multi-zone combustor 10 wherethe compressed gas may be mixed with fuel and combusted to produce afluid flow of high temperature fluids. These high temperature fluids aretransmitted to a turbine section in which energy of the high temperaturefluids is converted into mechanical energy for use in the production ofpower and/or electricity.

The multi-zone combustor 10 includes a combustor body 20, a pre-mixer 40and a stepped center body 60. The combustor body 20 includes a combustorliner 21, which is annular and formed to define a combustor section 211with a combustion zone therein, a combustor flow sleeve 22, which isprovided about the combustor liner 21 to define an annulus through whichat least the compressed gas produced by the compressor flows, and an endcover 23, which defines a head end 212 of the multi-zone combustor 10.The combustor section 211 is defined downstream from the head end 212with a mixing section 213 axially interposed therebetween.

The pre-mixer 40 is extendible from the head end 212 through the mixingsection 213 and may be annular in shape or provided as a series ofcavities in an annular array. In any case, the pre-mixer 40 is receptiveof a first quantity of fuel from a first fuel circuit 41 and a firstquantity of the compressed gas produced by the compressor. The firstquantity of the fuel and the first quantity of the compressed gas aremixed along an axial length of the pre-mixer 40 and output as a firstmixture at a first axial location 70 to a primary zone 80 of thecombustor section 211. The primary zone 80 is defined to extend aft froma forward portion of the combustor section 211 and may be radiallyproximate to the combustor liner 21.

With reference to FIGS. 1 and 2, the stepped center body 60 isdisposable in an annulus 61 defined within the pre-mixer 40 and includesat least an outer body 62 and an inner body 63. The outer body 62 isreceptive of a second quantity of fuel from a second fuel circuit 64 anda second quantity of the compressed gas produced by the compressor. Thesecond quantity of the fuel and the second quantity of the compressedgas are mixed along an axial length of the outer body 62 and output as asecond mixture at a second axial location 71, which is downstream fromthe first axial location 70, to a secondary zone 90 of the combustorsection 211. The secondary zone 90 is defined radially inwardly from theprimary zone 80 and is defined to extend aft from the second axiallocation 71. The second axial location 71 is provided at an axialdistance, L1, from the first axial location 70. The outer body 62 isthus configured to output the second mixture to the secondary zone 90 ata first radial and axial step 110.

The inner body 63 is disposable in an annulus 65 defined within theouter body 62. The inner body 63 is receptive of a third quantity offuel from a third fuel circuit 66 and a third quantity of the compressedgas produced by the compressor. The third quantity of the fuel and thethird quantity of the compressed gas are mixed along an axial length ofthe inner body 63 and output as a third mixture at a third axiallocation 72, which is downstream from the second axial location 71, to atertiary zone 100 of the combustor section 211. The tertiary zone 100 isdefined radially inwardly from the secondary zone 90 and is defined toextend aft from the third axial location 72. The third axial location 72is provided at an axial distance, L2, from the second axial location 71.The inner body 63 is thus configured to output the third mixture to thetertiary zone 100 at a second radial and axial step 120.

In accordance with embodiments, the axial distances, L1 and L2, may besimilar to one another or different from one another depending on designconsiderations and operability requirements.

The first fuel circuit 41, the second fuel circuit 64 and the third fuelcircuit 66 are independent from one another and separately controlledsuch that the first mixture, the second mixture and the third mixtureare fueled independently and separately. In this way, relativequantities of the fuel and the compressed gases in each can becontrolled independently and separately in accordance with anoperational mode of the multi-zone combustor 10. For example, duringfull speed, full load (FSFL) operation, the first mixture, the secondmixture and the third mixture may all contain fuel and compressed gases.By contrast, during turndown or part load operation, the second mixtureand the third mixture may contain compressed gases and substantiallyreduced amounts (i.e., none or trace amounts) of fuel.

As shown in FIG. 2, the outer body 62 may include a first row of vanes130 and the inner body 63 may include a second row of vanes 131. Inaccordance with embodiments, the first row of vanes 130 and the secondrow vanes may be configured to impart a swirl to the second mixture andthe third mixture, respectively. This swirl can be provided such thatthe second mixture and the third mixture are each output in aco-rotational condition or in a counter-rotational condition. In eithercase, the swirl may be provided with equal/similar swirl angles ordifferent swirl angles. Although the first row of the vanes 130 and thesecond row of the vanes 131 are illustrated as being disposed aft of thefirst axial location 70, it is to be understood that this is merelyexemplary and that the first row of the vanes 130 and the second row ofthe vanes 131 can be disposed forward, aft and/or coaxial with the firstaxial location 70.

With reference to FIG. 3 and, in accordance with further embodiments, atleast one or more additional radial and axial step(s) 140 may beprovided for the stepped center body 60. For clarity and brevity, onlyone additional radial and axial step 140 will be described, although itis to be understood that this is merely exemplary. Where the steppedcenter body 60 includes the additional radial and axial step 140, thestepped center body 60 further includes an additional body 141, which isdisposable between the outer body 62 and the inner body 63. Theadditional body 141 is independently and separately supplied with fueland compressed gases, which are mixed along an axial length of theadditional body 141 and output as a fourth mixture at a fourth axiallocation 142, which is downstream from the second axial location 71 andupstream from the third axial location 72, to the combustor section 211.The second axial location 71 is provided at an axial distance, L1, fromthe first axial location 70, the fourth axial location 142 is providedat an axial distance, L2, from the first axial location 70 and the thirdaxial location 72 is provided at an axial distance, L3, from the firstaxial location 70. The additional body 141 is thus configured to outputthe fourth mixture at the additional radial and axial step 140.

The additional body 141 may also include an additional row of vanes 143to impart swirl to the fourth mixture in a similar or differentdirection/angle as the first row of vanes 130 and/or the second row ofvanes 131. As above, although the first row of the vanes 130, the secondrow of the vanes 131 and the additional row of the vanes 143 areillustrated as being disposed aft of the first axial location 70, it isto be understood that this is merely exemplary and that the first row ofthe vanes 130, the second row of the vanes 131 and the additional row ofthe vanes 143 can be disposed forward, aft and/or coaxial with the firstaxial location 70.

In accordance with embodiments, the axial distances, L1, L2 and L3, maybe arranged with similar or different axial spacing from one anotherdepending on design considerations and operability requirements.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A multi-zone combustor, comprising: a pre-mixer configured to outputa first mixture to a primary zone of a combustor section; and a steppedcenter body disposable in an annulus defined within the pre-mixer andincluding: an outer body configured to output at a first radial andaxial step a second mixture to a secondary zone of the combustorsection, and an inner body disposable in an annulus defined within theouter body and configured to output at a second radial and axial step athird mixture to a tertiary zone of the combustor section.
 2. Themulti-zone combustor according to claim 1, wherein the first mixture,the second mixture and the third mixture are fueled separately.
 3. Themulti-zone combustor according to claim 1, wherein the second mixtureand the third mixture are each output in a co-rotation condition.
 4. Themulti-zone combustor according to claim 1, wherein the second mixtureand the third mixture are each output in a counter-rotation condition.5. The multi-zone combustor according to claim 1, wherein the secondmixture and the third mixture are each output with similar rotationangles.
 6. The multi-zone combustor according to claim 1, wherein thestepped center body further includes an additional body disposablebetween the outer body and the inner body and configured to output at athird radial and axial step a fourth mixture to a fourth zone of thecombustor section.
 7. A multi-zone combustor, comprising: a combustorbody having a head end, a combustor section downstream from the head endand a mixing section interposed between the head end and the combustorsection; a pre-mixer extendible from the head end through the mixingsection and configured to output at a first axial location a firstmixture to the combustor section; and a stepped center body disposablein an annulus defined within the pre-mixer and including: an outer bodyconfigured to output at a second axial location downstream from thefirst axial location a second mixture to the combustor section, and aninner body disposable in an annulus defined within the outer body andconfigured to output at a third axial location downstream from thesecond axial location a third mixture to the combustor section.
 8. Themulti-zone combustor according to claim 7, wherein the first mixture,the second mixture and the third mixture are fueled separately.
 9. Themulti-zone combustor according to claim 7, wherein the second mixtureand the third mixture include air and substantially reduced quantitiesof fuel during turndown operations.
 10. The multi-zone combustoraccording to claim 7, wherein the second mixture and the third mixtureare each output in a co-rotation condition.
 11. The multi-zone combustoraccording to claim 7, wherein the second mixture and the third mixtureare each output in a counter-rotation condition.
 12. The multi-zonecombustor according to claim 7, wherein the second mixture and the thirdmixture are each output with similar rotation angles.
 13. The multi-zonecombustor according to claim 7, wherein the stepped center body furtherincludes an additional body disposable between the outer body and theinner body and configured to output at a third radial and axial step afourth mixture to a fourth zone of the combustor section.
 14. Amulti-zone combustor, comprising: a combustor body having a head end, acombustor section downstream from the head end and a mixing sectioninterposed between the head end and the combustor section; a pre-mixerextendible from the head end through the mixing section and configuredto output at a first axial location a first mixture to the combustorsection; and a stepped center body disposable in an annulus definedwithin the pre-mixer and including: an outer body configured to outputat a second axial location downstream from the first axial location asecond mixture to the combustor section, and an inner body disposable inan annulus defined within the outer body and configured to output at athird axial location downstream from the second axial location a thirdmixture to the combustor section.
 15. The multi-zone combustor accordingto claim 14, wherein the first mixture, the second mixture and the thirdmixture are fueled separately.
 16. The multi-zone combustor according toclaim 14, wherein the second mixture and the third mixture include airand substantially reduced quantities of fuel during turndown operations.17. The multi-zone combustor according to claim 14, wherein the secondmixture and the third mixture are each output in a co-rotationcondition.
 18. The multi-zone combustor according to claim 14, whereinthe second mixture and the third mixture are each output in acounter-rotation condition.
 19. The multi-zone combustor according toclaim 14, wherein the second mixture and the third mixture are eachoutput with similar rotation angles.
 20. The multi-zone combustoraccording to claim 14, wherein the stepped center body further includesan additional body disposable between the outer body and the inner bodyand configured to output at a third radial and axial step a fourthmixture to a fourth zone of the combustor section.